Search Results

You are looking at 1 - 8 of 8 items for :

  • Forecasting x
  • Global Drought Information System - Drought Characterization, Occurrence, Driving Mechanisms, and Predictability Worldwide (GDIS Worldwide) x
  • All content x
Clear All
Mathew Barlow, Benjamin Zaitchik, Shlomit Paz, Emily Black, Jason Evans, and Andrew Hoell

parts of the region. The link to the tropical oceans has been used as a basis for statistical correction of model output, which has been shown to increase predictive skill for seasonal winter precipitation forecasts in northeastern Afghanistan, northern Pakistan, and the northern tier of the domain (Uzbekistan, Tajikistan, and Kyrgyzstan; Tippett et al. 2003 , 2005 ). The degree to which model improvements could extend the area of predictability or ocean information could be used directly for

Full access
Belen Rodríguez-Fonseca, Elsa Mohino, Carlos R. Mechoso, Cyril Caminade, Michela Biasutti, Marco Gaetani, J. Garcia-Serrano, Edward K. Vizy, Kerry Cook, Yongkang Xue, Irene Polo, Teresa Losada, Leonard Druyan, Bernard Fontaine, Juergen Bader, Francisco J. Doblas-Reyes, Lisa Goddard, Serge Janicot, Alberto Arribas, William Lau, Andrew Colman, M. Vellinga, David P. Rowell, Fred Kucharski, and Aurore Voldoire

) and aerosol–radiative forcings ( Kim et al. 2010 ). These effects can potentially interact with each other. For example, the variability of land surface conditions can affect the circulation over the ocean, which in turn can modify the SSTs and indirectly affect conditions over land ( Ma et al. 2013 ). The existence of significant impacts on WAM rainfall of slowly varying climate subcomponents indicates the potential for useful long-range forecasts ( Vellinga et al. 2013 ; Gaetani and Mohino 2013

Full access
Omar V. Müller, Ernesto Hugo Berbery, Domingo Alcaraz-Segura, and Michael B. Ek

indicating that a more realistic representation of surface conditions reduces model biases, many current numerical models, particularly those used for operational forecasts, still employ fixed land-cover types. Hence, they are unable to represent the additional sources of interannual variability owing to land-cover changes, as a result of either land-use changes or the vegetation’s degree of stress (e.g., during droughts, wet periods, or insect outbreaks). In other words, models that do not include

Full access
Lixia Zhang and Tianjun Zhou

topography and vegetation types differ greatly among these climatic zones, the distribution of precipitation is inhomogeneous. It is difficult to use one drought index to reasonably represent all features of droughts over the whole of East Asia. In northwest China, which is an arid/semiarid area, no drought index is able to represent the drought types and severity levels ( J. Wang et al. 2007 ). Great efforts have been devoted to monitoring, understanding, and forecasting drought over East Asia. The

Full access
Siegfried D. Schubert, Ronald E. Stewart, Hailan Wang, Mathew Barlow, Ernesto H. Berbery, Wenju Cai, Martin P. Hoerling, Krishna K. Kanikicharla, Randal D. Koster, Bradfield Lyon, Annarita Mariotti, Carlos R. Mechoso, Omar V. Müller, Belen Rodriguez-Fonseca, Richard Seager, Sonia I. Seneviratne, Lixia Zhang, and Tianjun Zhou

warm tropical North Atlantic can help define the shape and intensity of the drought episodes ( Seager et al. 2010 ; Mo and Berbery 2011 ). Notably, the effect of land surface–atmosphere interactions, in the form of soil moisture–precipitation coupling, is essential in the development of drought in southern South America ( Xue et al. 2006 ; Wang et al. 2007 ; Ma et al. 2010 ; Sörensson and Menéndez 2011 ). Barreiro and Diaz (2011) noted that improved seasonal forecasts over South America

Full access
Bradfield Lyon

deleterious consequences it is not surprising that across the Greater Horn, where rain-fed agriculture is the mainstay, where food security is often threatened ( Funk et al. 2008 ; Funk and Brown 2009 ), and where the largest contribution to electricity generation is hydropower ( Kaunda et al. 2012 ), that drought information is especially valued. Nor is the interest in drought information limited to assessments of current conditions or the provision of seasonal forecasts. Seemingly contradictory signals

Full access
Siegfried D. Schubert, Hailan Wang, Randal D. Koster, Max J. Suarez, and Pavel Ya. Groisman

trends (1979–2012) In this section, we utilize numerical simulations to provide further insight into the nature of recent variability and trends over Eurasia. These simulations take the form of full global reanalyses [MERRA and the Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim)], Atmospheric Model Intercomparison Project (AMIP)-style simulations using the Global Modeling and Assimilation Office (GMAO) GEOS-5 system, and simulations with more idealized SST

Full access
Richard Seager and Martin Hoerling

forced by anomalous heat sources over the warm tropical Pacific SST anomalies ( Hoskins and Karoly 1981 ). Trenberth et al. (1988) then applied linear wave theory to link the 1988 drought to the ongoing La Niña event and Palmer and Brankovic (1989) claimed to be able to produce important elements of the same drought within the European Centre for Medium-Range Weather Forecasts (ECMWF) numerical weather prediction model when forced by the observed SSTs. Explaining a seasonal drought is good

Full access